1. Field of the Invention
The present invention relates to an expansion valve, and more particularly, to an expansion valve, which has rectangular flow channels for assembling inlet and outlet pipes of an evaporator with an inlet pipe of a compressor and an outlet pipe of a condenser at an approximate right angle, and a guide part formed on the flow channel, thereby improving a mounting efficiency and reducing flow resistance and noise.
2. Background of the Related Art
In general, as shown in FIG. 1, a cooling system compresses working fluid, which performs thermal exchange with the outdoor air, into a liquefiable gas state of high temperature and pressure inside a compressor 1, and transmits it to a condenser 20.
The working fluid of the gas state is changed into a liquid state while passing the condenser 20 and induced to an expansion valve 30.
After that, the working fluid changed into a liquid state is changed into a wet-saturated vapor state of low temperature and pressure by a throttling action of the expansion valve 30, and induced to an evaporator 40 mounted inside an air conditioning case 50.
Next, the working fluid induced to the evaporator 40 is evaporated of itself by absorbing heat (latent evaporation heat), which is necessary for evaporation, from the surrounding air, and repeatedly performs the above cycle by being induced into the compressor 10 after being changed into a gas state.
Components of the above cooling system are installed at predetermined positions inside an engine room 61 and a passenger room 62 of a car respectively.
That is, the air conditioning case 50 is installed in the passenger room 62 divided by a dash panel 60, and other components are installed inside the engine room 61.
During the above circulation process of the working fluid, the working fluid of the inside of the evaporator 40 absorbs the outdoor air heat passing the outside of the evaporator 40 and thermally exchanges the outdoor air into a low temperature state, so that the inside of a car room can be cooled continuously.
However, when working fluid of a small amount and a highly thermal load is induced into the evaporator 40, as the working fluid is completely evaporated before reaching an outlet of the evaporator 40 and discharged to the compressor 10 in an overheated condition, it deteriorates a cooling efficiency and overheats the compressor 10. On the contrary, when working fluid of an excessive amount is induced into the evaporator 40 and a degree of superheat is too low, as a part of the working fluid remains at the outlet of the evaporator 40 in a liquid state and is induced into the compressor 10, it causes a damage of the compressor 10.
Therefore, the expansion valve 30 is installed between the condenser 20 and the evaporator 40 and expands the condensed working fluid to evaporate the working fluid in the evaporator 40, so that the working fluid can be evaporated in the evaporator 40 while maintaining a proper degree of superheat.
Hereinafter, for your convenience, a flow channel of the expansion valve 30 connected with an inlet pipe 41 of the evaporator 40 is named as a first flow channel 32, and a flow channel connected with an outlet pipe 42 of the evaporator 40 is named as a second flow channel 33.
FIG. 2 is a sectional view of the expansion valve. In brief, the expansion valve includes: a body 31 having the first flow channel 32, which has an inlet 32a and an outlet 32b of the same flow direction, and the second flow channel 33, which has an inlet 33a and an outlet 33b of the same flow direction, the first and second flow channel 32 and 33 being separated from each other at a predetermined interval; a head part 34 mounted on the upper portion of the body 31 and having a temperature-sensing room 34a filled with fluid, and a diaphragm 34b and a plate 34c displaced in the upward direction according to expansion and contraction of the fluid; a rod 35 disposed on the lower portion of the plate 34c and having an end portion extending to the first flow channel 32 through the second flow cannel 33, the rod 35 performing an axial reciprocating motion according to a displacement amount of the diaphragm 34b and the plate 34c; an elastic member 36 mounted on the first flow channel 32 to apply elasticity toward the rod 35; and a ball 37 disposed between the end portion of the rod 35 and the elastic member 36 for controlling a sectional area of the first flow channel 32.
The above conventional expansion valve 30 is installed on the outer surface or the inner surface of the air conditioning case 50. If the expansion valve 30 is installed on the outer surface of the air conditioning case 50, it can be installed on one of both sides of the dash panel 60 of the car body. That is, the expansion valve 30 can be installed in the passenger room 62 or the engine room 61 of the car.
Hereinafter, an example for installing the expansion valve 30 into the engine room 61 of the car will be described.
FIG. 3 is a briefly exploded perspective view showing a state in which the conventional expansion valve is installed in the engine room. In FIG. 3, the inlet pipe 41 and the outlet pipe 42 of the evaporator 40 passing the dash panel 60 are assembled to a first flange 70, connected to sides of the first and second flow channels 32 and 33 of the expansion valve 30, and then, coupled with screw holes 38 formed in a side of the expansion valve 30 by bolts 72.
Ends of pipes 11 and 21 respectively connected to an inlet side of the compressor 10 and to an outlet side of the condenser 20 are assembled to a second flange 71, connected to the other sides of the first flow channels 32 and 33 of the expansion valve 30, and then, coupled with the screw holes 38 of the expansion valve 30 by the bolts 72.
By the above structure, when an amount of the working fluid induced into the evaporator 40 is small, an outlet part of the evaporator 40 is overheated more than a set temperature due to a rapid thermal exchange, the temperature-sensing room 34a sensing the overheated temperature is expanded, the diaphragm 34b moves the rods in an axial direction, and the ball 37 interlocking with the rod 35 opens the first flow channel 32 more than before.
Therefore, the working fluid of an amount more than before is supplied to the evaporator 40 through the opened first flow channel 32, and then, evaporated by the thermal exchange with the outdoor air while maintaining the proper degree of superheat.
Meanwhile, when an amount of the working fluid induced into the evaporator 40 is large, a part of the working fluid remains in the outlet portion of the evaporator 40 in a liquid state to lower the temperature less than the set temperature, and thereby, the temperature-sensing room 34a sensing the low temperature is contracted, and at the same time, the elastic member 36 is moved in an opposite direction to the direction of the case that the rod 35 is expanded. So, the ball 37 interlocking with the elastic member 36 opens the first flow channel 32 less than before.
Therefore, the working fluid supplied to the evaporator 40 through the first flow channel 32 performs the thermal exchange with the outdoor air while maintaining the proper degree of superheat.
However, when the expansion valve 30 and the first and second flanges 70 and 71 are assembled to each other in the engine room 61 of a small area, if they are assembled to each other in a row, the pipes 11 and 21 connected with the second flange 71 greatly protrude toward the engine room 61, and so, it is difficult to install the expansion valve 30 due to restriction in an assembling space.
To solve the above problem, as shown in FIG. 4, a connection block 80, which has right-angled holes 81, is inserted between the first flange 70 and the expansion valve 30 to assemble the first flange 70 and the expansion valve 30 at a right angle.
That is, when the first flange 70 and the expansion valve 30 are assembled to each other at a right angle by the connection block 80, also the second flange 71 connected to the other side of the expansion valve 30 can be assembled at a right angle to the first flange 70.
Therefore, the pipes 11 and 21 assembled to the second flange 71 do not protrude toward the engine room 61, and are installed nearly along the dash panel 60, so that the restriction in the assembling space is reduced when assembling work is performed inside the engine room 61.
However, as the pipes 11, 21, 41 and 42 are connected at a right angle to reduce the restriction in the assembling space, the connection block 80 is needed additionally, it is inconvenient to assemble the components due to the assembling work in the small engine room 61, and productivity is lowered due to increase of manufacturing costs and the number of assembling processes as the number of necessary components is increased.
To solve the above problems, JP Patent Publication No. 2001-241808 discloses an expansion valve. In brief, as shown in FIG. 5, the expansion valve has a square pillar type valve body 90. The valve body 90 includes an inflow channel 91 directing from the evaporator to the compressor and an outflow channel 92 directing from the compressor to the evaporator, and the inflow channel 91 and the outflow channel 92 are formed on a rectangular side of the valve body 90.
Therefore, the above expansion valve increases a degree of freedom in installation of the expansion valve, and allows an easy alignment of the evaporator and the compressor inside the engine room.
However, in the prior art, as an inlet 91a and an outlet 91b for the working fluid are formed in the rectangular side to increase the degree of freedom in installation, the flow channel 91 for passing the working fluid is formed at a right angle, and so, it may cause increase of flow resistance and noise due to a sudden change of fluid flow.